Feeding solar power back into municipal grid: Issues andfinger-pointing

[Home Guy]

We have a residential energy program here in Ontario (Canada) that I
really don't agree with (called the Micro-Fit program) where the
electricity from roof-mounted solar panels is purchased by the
provincial power authority (OPA) at something like 80 cents per kw-hour
(a crazy-high fee that will have to be subsidized by somebody - ie the
general population, taxpayers, etc).

I believe all the details for this can be found here:

http://microfit.powerauthority.on.ca/

A neighbor of mine had a free evaluation done on his home to see how
many panels situated on his roof would generate how much electricity.

The problem he's facing is that two different levels of power
distribution (the city-owned municipal owned and operated company, and
the provincial or regional power supplier or distributor that either
supplies the electricity to our city or owns the high and medium-voltage
lines and sub-stations where the electricity is stepped down) are
pointing the finger at each other by stating that there is a capacity
problem caused by the other as the reason why his solar panel
installation (which he hasn't yet contracted to be installed) can't be
connected to the grid.

It's my impression that any electricy that he'd be generating would
essentially be 2-phase 208 volts (ie - identical to the service that
enters our homes) and this electricity would simply be inserted or wired
in parallel through a meter to his existing electrical service. I don't
see how the capacity (or lack thereof) of the sub-station serving our
corner of the city plays any role as to whether or not our local grid
can accept and utilize the estimated 5 or 6 kw that his panels are
likely to put out at maximum.

This issue has recently come up as indicated by this:

-----------------
The OPA is proposing that all new microFIT applications submitted on or
after December 8, 2010, would need an offer to connect from their local
distribution company before the OPA issues a microFIT conditional offer
of contract. The proposed rule change can be viewed here.

http://microfit.powerauthority.on.ca/Program-updates/2010-December-8-microFIT-Connection-Rule.php
------------------

According to this document:

http://microfit.powerauthority.on.ca/pdf/microFIT-Program-Overview.pdf

Page 18 shows the most likely connection scheme - which is to connect
the Microfit PV project to the grid on the customer's side of his load
meter (ie - "behind the meter" - the load meter that is).

My basic thesis here is that I think any argument about the capacity of
the "grid" (where-ever or what-ever the "grid" is) being at or near
capacity and thus the application for eligibility to get the green light
for approval is bogus. We are talking about installations that can't
generate more than 10 kw - and more likely would only generate 5 or 6 kw
on a mid-summer day, with the bulk of that energy being consumed by the
home owner's own AC unit (I'm sure) with little or none to spare to be
injected back into the neighborhood grid.

Comments?

 

[vaughn]

It's just a money thing. I shall have a 12% return on capital.

I would certainly be tempted by that deal. That's better than the long-term
return of the stock market. There are, however, other factors. I would need to
be convinced that the panels 1) would likely survive a hurricane and 2) their
installation would not damage my roofing system.

Vaughn

 

[The Daring Dufas]

The above comment is exactly right.
There is no technical problem. The PV array can be sized to overcome
any supply side issues. What comes in can equally well go out.
But see diversity factor.
http://en.wikipedia.org/wiki/Diversity_factor
This has the biggest bearing on the matter.
Sounds tome that there are politcal/financial matters yet unresovled.

I am having a 4Kwp array fitted to my roof in two weeks time. (UK)
It's just a money thing. I shall have a 12% return on capital.

Keep an eye on your solar array my friend, those things like air
conditioners around here are being stolen at an increasing rate.
People install them at their remote cabins or camps only to return
to a powerless abode. Thieves will steel them while a home owner
is asleep at night!

http://www.usedsolarpowerpanels.com/thieves-now-targeting-solar-panels.html

http://preview.tinyurl.com/3cc3rkl

TDD

 

[Home Guy]

In other words, if it's 100F at 3PM, what would happen?
Would everyone with solar have their AC on and be either taking
power from the grid or at least not giving it back? Or because
of being paid 80C a kwh to generate electricity, will people be
putting in large systems and leaving their AC off?

Under the terms of the Ontario Microfit program, you (the home owner)
with a (typical) 3kw to 6kw solar array, will be paid 80 cents /kwh for
20 years. The going rate for buying electricity in this market at the
residential level is (when you factor in all the various transmission
and delivery costs) about 15 cents / kwh.

You are paid 80 cents / kwh for *any* electricity leaving your array (a
billing meter is installed right after your invertors). It doesn't
matter if your own home (AC unit, etc) will suck 100% of that solar
energy with none of it going back into the grid. In fact, it's probable
that on that hot summer day that your home will still be pulling energy
from the municipal grid - just not as much because of the contribution
from your own panels.

Now is that the real reason behind what's going on? Don't know,
but it's certainly theoretically possible.

There has been some mention of a PF (power factor) issue when it comes
to these panels.

But still - you can't push more electricity onto a network than the load
is asking for (given that your invertors are functioning correctly I
guess).

 

[[email protected]]

Or because of being paid 80C a kwh to generate electricity,
will people be putting in large systems and leaving their AC off?
If the latter, then it would seem to me that taken together
enough solar panel systems could put more power into the
distribution system than it could handle.

I believe that 10 kw is the maximum size for micro-fit pricing,
in Ontario. per property.
.. now available for roof-top only - formerly rural free standing
tracking were elegible. ?
Each individual property/service will have specific limitations -
.. there's old crappy services out there ! fer shur.
but - BIG but - I would demand hard facts from my distribution
company - about any specific "grid" limits - that would be
restrictive to a 10 kw solar ...
Don't let them snow-job you - by saying they have to now plan for
all your neighbours installing 10 kw solar ...
My understanding is that these micro solar will be connected
through their own meter ? so the property owner will not be able to
affect the "sales" by adjusting his demand....

 

[[email protected]]

But still - you can't push more electricity onto a network than the load
is asking for (given that your invertors are functioning correctly I
guess).

I guess , not.

 

[Tom P]

I would certainly be tempted by that deal. That's better than the long-term
return of the stock market. There are, however, other factors. I would need to
be convinced that the panels 1) would likely survive a hurricane and 2) their
installation would not damage my roofing system.

Vaughn

Up front - you should in any case arrange for your building insurance to
be extended to include cover for the panels. Why? Because if it does
blow away in a gale or catch fire or whatever and they don't know about
it, in the worst case the insurance could refuse to pay for the damage.
The additional insurance for my roof panels costs here (Germany) €88
per year. There are cheaper offers but I preferred to use the same
company for all the building related insurance to avoid any finger
pointing problems in the event of a claim.
It is possible that the insurer might demand that the roof structure be
checked by a surveyor before you start work. As far as any damage to the
roof during installation, a reputable installation/roofing company
should in any case have professional liability insurance.

 

[Tom P]

We have a residential energy program here in Ontario (Canada) that I
really don't agree with (called the Micro-Fit program) where the
electricity from roof-mounted solar panels is purchased by the
provincial power authority (OPA) at something like 80 cents per kw-hour
(a crazy-high fee that will have to be subsidized by somebody - ie the
general population, taxpayers, etc).

I believe all the details for this can be found here:

http://microfit.powerauthority.on.ca/

A neighbor of mine had a free evaluation done on his home to see how
many panels situated on his roof would generate how much electricity.

The problem he's facing is that two different levels of power
distribution (the city-owned municipal owned and operated company, and
the provincial or regional power supplier or distributor that either
supplies the electricity to our city or owns the high and medium-voltage
lines and sub-stations where the electricity is stepped down) are
pointing the finger at each other by stating that there is a capacity
problem caused by the other as the reason why his solar panel
installation (which he hasn't yet contracted to be installed) can't be
connected to the grid.

It's my impression that any electricy that he'd be generating would
essentially be 2-phase 208 volts (ie - identical to the service that
enters our homes) and this electricity would simply be inserted or wired
in parallel through a meter to his existing electrical service. I don't
see how the capacity (or lack thereof) of the sub-station serving our
corner of the city plays any role as to whether or not our local grid
can accept and utilize the estimated 5 or 6 kw that his panels are
likely to put out at maximum.

This issue has recently come up as indicated by this:

-----------------
The OPA is proposing that all new microFIT applications submitted on or
after December 8, 2010, would need an offer to connect from their local
distribution company before the OPA issues a microFIT conditional offer
of contract. The proposed rule change can be viewed here.

http://microfit.powerauthority.on.ca/Program-updates/2010-December-8-microFIT-Connection-Rule.php
------------------

According to this document:

http://microfit.powerauthority.on.ca/pdf/microFIT-Program-Overview.pdf

Page 18 shows the most likely connection scheme - which is to connect
the Microfit PV project to the grid on the customer's side of his load
meter (ie - "behind the meter" - the load meter that is).

My basic thesis here is that I think any argument about the capacity of
the "grid" (where-ever or what-ever the "grid" is) being at or near
capacity and thus the application for eligibility to get the green light
for approval is bogus. We are talking about installations that can't
generate more than 10 kw - and more likely would only generate 5 or 6 kw
on a mid-summer day, with the bulk of that energy being consumed by the
home owner's own AC unit (I'm sure) with little or none to spare to be
injected back into the neighborhood grid.

Comments?

The bark may be worse than the bite. The company who did my PV
installation also did the entire beaurocratic paperchase for me. They
sent me a whole pile of application forms to fill in, and I sent them
all back with a limited power of attorney to let them get on with it.

I can understand that the grid operators need to know how many PV
installations there are and how they are all connected.

 

[Home Guy]

I believe that 10 kw is the maximum size for micro-fit pricing,
in Ontario. per property.

Correct. Anything over 10 kw falls into a different program - called
"Fit". But given the geographic area of Ontario (mostly above 42
degrees latitude) you'd need a pretty big house with no tree shading to
generate anything close to 10 kw.

.. now available for roof-top only - formerly rural free standing
tracking were elegible. ?

The microfit program really only started in late 2009. Up until some
point in 2010, you got 80 cents / kwh regardless if it was roof-top or
ground mounted (basically the early program documentation wasn't clear
enough or didn't differentiate between the two styles). It was only by
mid 2010 that they announced a different price rate for ground mounted
panels - I think it's 60-odd cents. Anyone that already had
ground-mounted was grandfathered in at the roof-top rate (80 cents).

Each individual property/service will have specific limitations -
.. there's old crappy services out there ! fer shur.

It's a scam, really. The local and regional electricity providers (we
generally call the electricity service the "hydro" service, because
historically Ontario's electricity was first generated by hydro-electric
facilities in Niagara falls) does not really want to see these solar
panels on residential rooftops - I suppose they don't need the hassle of
new sources for problems with the grid, power-factor issues,
competition, etc.

When you get denied to connect your panels to the grid, it's not really
based on the wiring between your house and your distribution transformer
(nobody comes out to look at that). The denial is based on the capacity
or condition of the regional substation serving your corner of the city
- something for which I can't really imagine how it's involved in the
transmission of the energy your panels are going to put into the grid.

The fact is that unless you turn off your AC unit on the sunniest /
hottest days of the summer, the energy your panels are putting out will
be 100% consumed by your own home's load, with none of it going out to
the grid. But you'll still get paid 80 cents / kwh because the payment
meter is placed right after the invertor output before it goes anywhere
else.

My understanding is that these micro solar will be connected
through their own meter ? so the property owner will not be
able to affect the "sales" by adjusting his demand....

You're sort of correct.

Yes, the panels have their own meter. But nothing the owner can do with
his home's load will affect billing or revenue from the panels - because
he's paid for any and all kw being generated by the panels - even if
none of those kw are technically leaving his own home.

 

[[email protected]]

I would certainly be tempted by that deal. That's better than the long-term
return of the stock market.

As long as the government can rob peter to pay you.

 

[Winston]

harry wrote:
(...)

It's not taxpayer funded. It's funded by other electricity users in
the UK so ultimately increasing the price of electricity. Still, I
intend to be a receiver of money rather than a giver.

Why does this remind me of the famous Whimpy quote:
"I'll gladly pay you Tuesday for a hamburger today" ?

http://www.urbandictionary.com/

"From Popeye cartoons. Line often uttered by Popeye's portly friend
Wimpy. Of course, "Tuesday" would never come, and so Wimpy
constantly secured himself a free lunch. Thus the line is used to
jokingly indicate that one would like to "borrow" something without
any real intention of ever paying you back."


--Winston

 

[daestrom]

Under the terms of the Ontario Microfit program, you (the home owner)
with a (typical) 3kw to 6kw solar array, will be paid 80 cents /kwh for
20 years. The going rate for buying electricity in this market at the
residential level is (when you factor in all the various transmission
and delivery costs) about 15 cents / kwh.

You are paid 80 cents / kwh for *any* electricity leaving your array (a
billing meter is installed right after your invertors). It doesn't
matter if your own home (AC unit, etc) will suck 100% of that solar
energy with none of it going back into the grid. In fact, it's probable
that on that hot summer day that your home will still be pulling energy
from the municipal grid - just not as much because of the contribution
from your own panels.


There has been some mention of a PF (power factor) issue when it comes
to these panels.

But still - you can't push more electricity onto a network than the load
is asking for (given that your invertors are functioning correctly I
guess).

One issue that utilities worry about is the available fault current.
The breaker main in a typical home might be able to safely interrupt as
much as 10 kA. The current of a dead short in your home is a function
of the sources feeding it. If the total is less than 10 kA, the breaker
opens and everyone's safe. If the sources could feed more than 10 kA,
the breaker may fuse/melt and the fault will continue to draw current
and your house burns down.

So when adding new sub-station equipment and generating units, they have
to calculate the available fault currents and make sure it's still under
the breaker/protection equipment capabilities.


All that being said, I can't honestly think a small grid-tie PV
installation would make enough of a difference to be a problem. Worst
case is your neighbor has a fault and the combined current from the
utility and your PV setup exceeds his breaker's interrupting capacity.

But a good EE could sharpen his pencil once and do the calcs and
probably find there is a wide margin between what the pole transformer
can supply to a fault and what your PV system would supply. They're
probably just to worried about their liability to bother.

daestrom
P.S. Maybe if every household in a whole development had such a
microFIT installation? I'd have to see the numbers though to believe it.

 

[daestrom]

Correct. Anything over 10 kw falls into a different program - called
"Fit". But given the geographic area of Ontario (mostly above 42
degrees latitude) you'd need a pretty big house with no tree shading to
generate anything close to 10 kw.


The microfit program really only started in late 2009. Up until some
point in 2010, you got 80 cents / kwh regardless if it was roof-top or
ground mounted (basically the early program documentation wasn't clear
enough or didn't differentiate between the two styles). It was only by
mid 2010 that they announced a different price rate for ground mounted
panels - I think it's 60-odd cents. Anyone that already had
ground-mounted was grandfathered in at the roof-top rate (80 cents).


It's a scam, really. The local and regional electricity providers (we
generally call the electricity service the "hydro" service, because
historically Ontario's electricity was first generated by hydro-electric
facilities in Niagara falls) does not really want to see these solar
panels on residential rooftops - I suppose they don't need the hassle of
new sources for problems with the grid, power-factor issues,
competition, etc.

When you get denied to connect your panels to the grid, it's not really
based on the wiring between your house and your distribution transformer
(nobody comes out to look at that). The denial is based on the capacity
or condition of the regional substation serving your corner of the city
- something for which I can't really imagine how it's involved in the
transmission of the energy your panels are going to put into the grid.

As I said in another post, one concern is how much fault current can be
drawn from the system. If there is a largish substation and several PV
generators on it, then the total current feeding into a fault *could* be
higher.

If that fault happens to be in someone's home and it exceeds the
*interrupting* capacity of their main breaker, the breaker may not be
able to isolate the fault and their house burns down.

It would seem to me that it would take a large number of PV
installations to really raise the possible fault current very much
though. Maybe they just don't want to pay an engineer to figure it out.

daestrom
P.S. Note that the available fault current has nothing to do with the
circuit breaker's trip setting and only loosely related to the
individual inverter output capability.

 

[[email protected]]

It's not taxpayer funded. It's funded by other electricity users in
the UK so ultimately increasing the price of electricity. Still, I
intend to be a receiver of money rather than a giver.

There is still a peter being robbed at the government's insistence, dope.

 

[Vaughn]

dope.

Well, we've degenerated to name-calling. I don't expect we'll see much more
useful discussion from this thread.

Vaughn

 

[[email protected]]

Well, we've degenerated to name-calling. I don't expect we'll see much more
useful discussion from this thread.

I can't help it if you don't like facts. harry *is* a dope.

 

[m II]

One issue that utilities worry about is the available fault current.

Please be informed that the Josepi clown has been forging my username
for a few weeks now. His provider is doing nothing to stop the forgeries.

Check the headers when in doubt. It's times like these I wonder about
the maturity levels of some, no doubt very ill, people.


mike

 

[m II]

One issue that utilities worry about is the available fault current.

Please be informed that the Josepi clown has been forging my username
for a few weeks now. His provider is doing nothing to stop the forgeries.

Check the headers when in doubt. It's times like these I wonder about
the maturity levels of some, no doubt very ill, people.


mike

 

[daestrom]

in message One issue that utilities worry about is the available fault current.
The breaker main in a typical home might be able to safely interrupt as
much as 10 kA. The current of a dead short in your home is a function
of the sources feeding it. If the total is less than 10 kA, the breaker
opens and everyone's safe. If the sources could feed more than 10 kA,
the breaker may fuse/melt and the fault will continue to draw current
and your house burns down.

So when adding new sub-station equipment and generating units, they have
to calculate the available fault currents and make sure it's still under
the breaker/protection equipment capabilities.


All that being said, I can't honestly think a small grid-tie PV
installation would make enough of a difference to be a problem. Worst
case is your neighbor has a fault and the combined current from the
utility and your PV setup exceeds his breaker's interrupting capacity.

But a good EE could sharpen his pencil once and do the calcs and
probably find there is a wide margin between what the pole transformer
can supply to a fault and what your PV system would supply. They're
probably just to worried about their liability to bother.

daestrom
P.S. Maybe if every household in a whole development had such a
microFIT installation? I'd have to see the numbers though to believe it.


-----------------

The fault capacity of a household main breaker or fuses is not an issue,
unless very old technology, like you.
One hundred feet of twisted triplex supply cable limits faults to well
within the fault tolerances.

Got some numbers/calculations to support that? Is that including the
next door neighbors with their PV installation?

daestrom

 

[Han]

Actually you can and do as I understand it. To pump power into the
grid you supply a slightly higher voltage than what is in the line.
When spread over all the loads on the grid the change in voltage is
next to nothing. If enough inputs are made by others the voltage will
rise, and it is allowed to so long as it stays within a certain
range. If it is going to go too high it is up to the utility to
reduce the input at sources they control.

I have no idea how it works exactly, but here in North Jersey PSE&G has
been putting up solar panels on their (I think) utility poles. Each one
is maximum 200 Watts at 110V, feeding directly into the grid the poles
carry. This is a link + picture in another town not too far away (1 line):
<http://www.nj.com/hudson/index.ssf/2011/02/pseg_installing_solar_panels_
o.html>
or:
<http://tinyurl.com/3dvgy7r>